The present invention relates to a heat exchanger, particularly to a duplex heat exchanger in which a radiator and a condenser for a vehicle are integrated.
According to the invention proposed in Japanese Unexamined Patent Publication 10-231724, for example, the cooling fins of the heat exchanger have a protrusion portion protruded from an end of the tube in the width direction of the tube to the direction perpendicular to the longitudinal direction of the tubes to increase the radiation area, thus improving the radiation ability of the heat exchanger. The width direction of the tube is a direction perpendicular to the longitudinal direction of the tube.
As is well known, the louvers on the cooling fin (called a fin hereinafter) are formed in louver board style by cutting and setting up part of the fin, and disturb the airflow around the fin to suppress growth of the temperature boundary layer, thereby improving the heat transfer coefficient between the airflow and the fin. However, since the louvers disturb the airflow, the resistance to the airflow passing through the heat exchanger may be increased.
In addition, since the louver is formed by cutting and setting up part of the fin, the thermal conductive area of the fin extending to the end of the protrusion portion is decreased, and thereby a sufficient amount of heat may not be conducted from the tube to the fin, and the improvement in radiation ability appropriate to the increase in radiation area may, accordingly, not be achieved.
It is therefore an object of the invention to improve the heat exchanging ability of a heat exchanger having fins protruded from an end of the tube in the width direction thereof.
In order to achieve the above object, a heat exchanger according to the present invention comprises a plurality of tubes (111, 121) in which fluid flows and which extend to the direction perpendicular to the direction of airflow, and fins (112, 122) which are provided on the outer surface of the tubes (111, 121) to accelerate the heat exchange between air and the fluid, wherein the fins (112, 122) have protrusion portions (112e, 122e) protruded from an end of the tubes (111, 121) in the width direction of the tube to the direction perpendicular to the longitudinal direction of the tubes (111, 121), and uneven portions (112f, 122f) are formed on the protrusion portions (112e, 122e), without cutting part of them, to increase the surface area of the fins (112, 122).
In this embodiment, the surface area of the protrusion portions (112e, 122e) may be increased without decreasing the thermal conductive area extending to the end of the protrusion portions (112e, 122e), and thereby a sufficient amount of heat may be conducted from the tubes (111, 121) to the fins (112, 122), especially to the protrusion portions (112e, 122e), and the improvement of radiation ability appropriate to the increase of radiation area may be achieved accordingly
In addition, the uneven portions (112f, 122f) do not disturb the airflow as much as the louvers because the uneven portions are not formed by cutting part of the fins in contrast to the louvers, thus decreasing the airflow resistance more than the louver. Although the heat transfer coefficient of the protrusion portions (112e, 122e) may be lower than that in case that the louvers are provided, the surface area of the protrusion portions (112e, 122e) are increased without decreasing the thermal conductive area of the protrusion portions (112e, 122e), and the air volume is increased due to the decrease of airflow resistance, and thereby the radiation ability may be improved,
Another embodiment of the present invention comprises a plurality of tubes (111, 121) in which fluid flows and which extend to the direction perpendicular to the direction of airflow, and fins (112, 122) which are provided on the outer surface of the tubes (111, 121) to accelerate the heat exchange between air and the fluid, and on which louvers (112d, 122d) are formed in louver board style by cutting and setting up part of the fins (112, 122), wherein the fins (112, 122) have protrusion portions (112e, 122e) protruded from an end of the tubes (111, 121) in the width direction of the tube to the direction perpendicular to the longitudinal direction of the tubes (111, 121), and the louvers (112d, 122d) formed on the protrusion portions (112e, 122e) are different from the louvers (112d, 122d) formed on the other portions than the protrusion portions (112e, 122e) of the fins (112, 122).
In this embodiment, the airflow resistance of the protrusion portions may be decreased, and the improvement in radiation ability appropriate to the increase of radiation area may be achieved accordingly.
The heat exchanger of another embodiment of the present invention is a duplex heat exchanger comprising a first heat exchanger (110) which is a heat exchanger according to the present invention, and a second heat exchanger (120) which is a heat exchanger according to the present invention arranged in series with the first heat exchanger (110) in the direction of airflow, wherein the protrusion portions (112e) of the first heat exchanger (110) are protruded to the second heat exchanger (120), and the protrusion portions (122e) of the second heat exchanger (120) are protruded to the first heat exchanger (110).